[libc-commits] [libc] [llvm] [Flang-RT][libc] LLVM-independent unittests (PR #164794)

[David Spickett via libc-commits]

https://github.com/DavidSpickett commented:

I'm a bit under the weather at the moment so I have only read this briefly. My takeaways:
* The impact to the flang-rt tests is minimal.
* If someone did use llvm things in those tests, it would fail at link time (perhaps earlier if the include paths are also not added anymore).
* Doing this for just flang-rt right now is in theory fine, because compiler-rt has done the same thing in its own way.
* There's an impact on cmake used by other projects though, so we need some review from them.

> For instance, Clang is built using gcc which uses libstdc++, but the runtimes is built by Clang which can be configured to use libcxx by default.

In our buildbot we attempt to link everything to the libc++ from the installed clang, so in theory we can pass enough flags to fix the issue in other ways (though I never did find the right runes to do it).

Your example though, I see why that cannot be done. Even if we added test specific library choices, those tests would link to a runtime library linked against something else.

Saying that you can't run tests in this scenario, of course we want to avoid that.

I will try this patch with our buildbot config, but expect it to be about a week before I get time to do so.

https://github.com/llvm/llvm-project/pull/164794